The discovery of subsystem codes [1]}, [2]} led to the study of sparse
subsystem codes, first in the context of topological subsystem codes, of which there are now
many examples [3]}, [4]}, [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]}.
These codes are all concerned with the case \(k=O(1)\)  and all achieve distance
\(d=O(\sqrt{n})\) .
